Five years after starting his first job with a landscaping crew in the suburbs of Seattle, Fredi Dubon decided he had enough and called it quits. The work days were long, sometimes 12 hours, but a bigger problem was having to inhale exhaust from his gas-powered leaf blower.

The fumes tended to be harshest in the cool mornings or when he ran his aging machine in the narrow yards of condo buildings. Eventually Dubon, a 28-year-old immigrant from El Salvador, said he was getting migraine headaches “pretty much every day,” a problem that both he and a doctor who examined him attributed to the exhaust belched by the blower.

Fredi Dubon quit his job with a landscaping company in the Seattle suburbs after getting migraines “pretty much every day,” which his doctor attributed to inhaling exhaust from his leaf blower. Those machines and others with small engines put out large amounts of smog-producing chemicals, plus microscopic ultrafine particles that can cause potential health problems like lung cancer, heart disease and asthma, experts say.

Photo courtesy of Fredi Dubon

Yet the headaches that Dubon suffered – until he joined a landscaping company that used electric machines – provide only a whiff of the possible hazardsfrom gasoline-fired lawn and garden equipment.

California’s approval of tightened air quality regulations, campaigns for leaf blower bans by local activists around the country, and resolutions passed by the state medical societies of New York and Massachusetts highlighting health risks are beginning to draw more attention to the issue. At the same time, landscaping equipment manufacturers once accused of resisting a shift to electric machines, and that still push back against environmental regulations, are offering more of the so-called zero-emissions options.

Scant research exists on the potential health impact of emissions from the millions of gas-powered leaf blowers, lawn mowers, trimmers and related equipment now in use. Yet, despite improvements, these machines still emit toxic contaminants such as carcinogenic benzene as well as surprisingly large amounts of other smog-forming chemicals.

In fact, according to Environmental Protection Agency estimates, emissions of smog-producing substances from mowers, blowers and other small off-road engines in 2016 were 81 percent as high as the amount from standard sedans. In the air pollution-plagued Los Angeles area, this category is projected to become a bigger contributor to smog than autos will be by around 2020.

Perhaps most worrisome, the gas engines release high concentrations of microscopic ultrafine particles, as recently confirmed in tests commissioned by FairWarning. Ultrafine particles are unregulated, but scientists increasingly believe they are a serious danger. That threat is particularly true for landscaping workers, but also a potential concern for other adults and children who are exposed. Ultrafine particles are 0.1 of a micron, or roughly one-thousandth the width of a human hair.

“The basic idea is that the smaller the particle, the deeper it can be inhaled into the lungs, and the more potential it has then to cause health problems” such as lung cancer, heart disease, strokes, asthma and other respiratory ailments, said Jo Kay Ghosh, an epidemiologist and the health effects officer for the South Coast Air Quality Management District, a pollution control agency covering much of smoggy Southern California. Ultrafine particles also can pass through cell membranes and slip into the bloodstream.

Unpublished, preliminary research by California regulators last year underscored such concerns. The California Air Resources Board’s limited testing, which is being followed up with a more formal study,suggested that the equipment operators were exposed to at least 10 times more ultrafine particles than if they were standing beside a busy roadway.

The basic idea is that the smaller the particle, the deeper it can be inhaled into the lungs, and the more potential it has then to cause health problems

Jo Kay Ghosh, epidemiologist and health effects officer for the South Coast Air Quality Management District

For workers who earn their living operating such equipment, “This is extremely alarming,” said Michael T. Benjamin, chief of the board’s monitoring and laboratory division, at a hearing lastNovember.

More recent testing conducted by a consulting firm for FairWarning, involving six workers who were monitored while using 16 pieces of gas-powered equipment, detected even more dramatic surges of ultrafine particles. In one instance, ultrafine particle levels around an 11-year-old leaf blower were 50 times higher than at a nearby clogged intersection at rush hour. In same round of tests, with a 2017 model leaf blower, the ultrafine particle level was more than 40 times higher than at the busy intersection.

Standard, disposable “N95” masks or respirators available at hardware stores can provide protection against exhaust particles – if they are fitted properly, which isn’t always easy. It takes more specialized respirators to filter out gases such as benzene. But due to cost, discomfort and lack of information, many workers don’t get any kind of respiratory protection.

The air pollution puts yet another burden on the nation’s roughly 1 million landscaping workers, who frequently are low-income immigrants with few job alternatives. They also often endure intense leaf blower noise, which a Centers for Disease Control report this year said can cause permanent hearing loss.

Landscaping workers commonly say they feel the effects of breathing exhaust from gas-powered machines. The issue helped spur Dubon, the Seattle-area worker who complained of headaches, to begin last year leading job safety workshops for Casa Latina, a nonprofit day labor center and advocacy organization.

Some of the workers Dubon meets who use gas-powered equipment, he said, tell him “they feel dizzy or nauseous” after operating the machines.

Yet landscaping workers often are resigned to the fumes as well to the noise and vibrations from their gas-powered machines. “You know you need to earn money and you have to work,” said Sergio Maldonado, a 35-year-old Guatemalan immigrant who has done landscaping in Miami for 18 years.

He added: “If you don’t do it, and you’re working for another person, they’ll fire you, and then who is going to bring home food?”

Aside from possible hazards to landscaping workers, the gas-powered equipment pollutes the air breathed by everyone. That factor spurred the California Air Resources Board, a national leader in air-quality regulation, in November to approve tighter requirements for mowers, blowers, chainsaws and other small off-road engines, with a broader round of restrictions expected within a few years.

You think about how much focus there is on reducing emissions from cars, and rightfully so, but how little we focused on these engines

Bill Magavern, policy director for the Coalition for Clean Air

The small off-road engines category is giving the auto a run for its money as a source of emissions that lead to smog, in part because cars burn gasoline much more cleanly than they once did. In one comparison, California officials say the contamination from running a top-selling leaf blower for just one hour matches the emissions from driving a 2016 Toyota Camry for 1,100 miles, the distance from Los Angeles to Denver. The pollutants in the leaf blower-versus-car comparisons are oxides of nitrogen and reactive organic gases.

“You think about how much focus there is on reducing emissions from cars, and rightfully so, but how little we focused on these engines,” said Bill Magavern, policy director for the Coalition for Clean Air, a California-based advocacy group. Magavern called the emissions comparisons “stunning” and added, “It just, to me, shows why we really need to pay a lot more attention to reducing emissions from this sector.”

Federally, the EPA generally has followed California’s lead in regulating emissions from landscaping equipment.

But the industry that makes these machines, which last year had estimated wholesale sales in the U.S. approaching $11 billion, historically has fought hard to fend off regulation. A high-profile battle erupted in 2003 when Briggs & Stratton – which describes itself as the world’s largest producer of gasoline engines for outdoor power equipment – unsuccessfully tried to thwart a new round of rules in California. The company persuaded then-U.S. Sen. Kit Bond of Missouri to push an amendment intended to strip states of the ability to adopt air quality standards tougher than federal rules for small off-road engines. Bond said he was trying to save jobs at Briggs & Stratton plants in his state.

California lawmakers resisted; eventually a compromise was reached leaving California’s authority intact but barring other states from adopting tougher-than-federal standards. And now, given that no one expects the Trump administration to take new steps to reduce air pollution around the country, “you’ve got a situation where even though California can move ahead legally…the rest of the country is basically shit out of luck,” said Frank O’Donnell, president of the Washington, D.C., nonprofit group, Clean Air Watch.

This story was produced by FairWarning, a nonprofit news organization focused on public health, consumer and environmental issues. FairWarning's reporting was supported by a grant from the Fund for Investigative Journalism.